Added to the latest version (21.1.4).
However, receipts and payments share the same email template.
If you want email template specific to receipts and another one specific to payments. Then use the following logic.
{% if title == "Receipt" %}
Text for receipts
{% endif %}
{% if title == "Payment" %}
Text for payments
{% endif %}
This way you can control what is generated for emails based on the document title.